Moisture exchange modules are described in the prior art. By way of example, JP 2002-3 03 435 shows a module in which the cross section of flow increases from the line element, which is arranged perpendicular to the module, to the cross section of that part of the bundle of hollow fibre membranes through which gas is to flow.
This gives rise to the problem that the distribution of the flow becomes very uneven over the cross section of the bundle of hollow fibres through which gas is to flow, in particular as the diameter of that part of the bundle of the hollow fibre membranes through which gas is to flow increases. A similar structure enabling medium to flow onto the entire available cross section of the bundle of hollow fibre membranes analogously to the abovementioned Japanese document would therefore be highly inefficient.
In the attempt to construct a moisture exchange module that is as compact as possible, however, it is now very important to achieve a highly uniform distribution over the cross section of the bundle of hollow fibre membranes through which gas is to flow, so that as far as possible the entire surface area of all the hollow fibre membranes can be used efficiently, and consequently a bundle of hollow fibre membranes that is as short as possible is achieved. However, this should also be associated, as before, with a compact inflow region, i.e. an inflow region of the shortest overall length possible.
Furthermore, DE 26 46 358 C2 shows, from the field of dialysis, a hollow fibre arrangement having a tangential inlet which opens out into an annular space. DE 26 60 630 C2 also shows structures of this type.